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## Mesh processing toolbox

version 1.2 (5.25 MB) by
Some useful tools for mesh processing

Updated 15 Aug 2020

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Please first check the doc tab on the right to get some relevant and functional examples of this toobox functions.

%% DESCRIPTION

This package is a mesh processing toolbox which aim at providing a command line mesh lab in Matlab (R) console. It is designed to deal with and process triangular meshes.
Quadrangular meshes as well as sorted edge lists are also possible as inputs thanks to "quad2trimesh" and "rebuild_triangulation_from_edge_list" conversion functions.

%% HELP / DOC

A basic help is included in the header of each source file. It especially includes descriptions of input and output arguments (format, class, role, size, etc).
Just like for any Matlab (R) function, typewrite "help my_mesh_processing_file" or "doc my_mesh_processing_file"  in Matlab console to see it.

%% DATA FORMATS & HYPOTHESIS ON THE MESH

Most of the functions included take very common and widely used data structures as input and output arguments :

- V : the vertex set / point cloud. Real matrix of doubles. size(V) = [nb_vertex,3].
- T : the triangulation / triangle set. Positive integer matrix of doubles. size(T) = [nb_triangles,3].
- E : the edge set. Positive integer matrix of doubles. size(T) = [nb_edges,2].

where :

- A vextex is a 1 x 3 row double vector of real numbers.
- A triangle (or a triplet) is a 1 x 3 row double vector of positive integers.
- An edge is a 1 x 2 row double vector of positive integers.

By default, and unless exceptions, vertices and triangles arguments are index based.

Another common argument is ngb_degre which corresponds to the neighborhood degre whished on the mesh, and which is used to find one vertex neighborhood.
For commun usages, this value is in the range |[1 ; 4]|. Tune it relatively to the local curvature of your mesh. CPU time is an increasing function of ngb_degre.

%% TESTS

Use .mat data files provided in /data for test and example files.
Most of the functions and every important ones have been tested in a dedicated file named : test_my_function.m

Note that no mesh reader or writer is provided in this toolbox since there already exist enough satisfying ones coded in Matlab.
Then to create your own .mat file for vertex set V and triangle set T, just use the command save('path_to_my_file/my_file.mat','V','T');

All the code included in this toolbox is the result of my unique personal own work and effort in 2020, and going on for upcoming updates.

Each one of the algorithms / functions included have been independently tested, however I cannot provide any warrantee of any kind about them. Use them at your own risk.

This toolbox and its content is free of use and distribution as long as you respect the following condition : this desciption_read_me file must be included as well as each function header must be preserved.

Modification of any kind are done under your own, only, and unique responsability.

Please report me any bug (with data set used and code) or suggestion at nicolas.douillet (at) free.fr

%% KNOWN LIMITATIONS

Though each function is vectorized at maximum, this toolbox do not use nearest neighbor searcher yet, so main limitations consist in CPU time and data volume, especially for Matlab (R) display functions.

For this reason, appropriate usage of this toolbox is for light / medium size mesh processing (< 50k triangles).

One of the main limitations known yet is the algorithm in remove_self_intersecting_triangles for large meshes, since the number of possible triangle pair combinations grows very quickly.

For a similar reason ismesh2Dmanifold function is also pretty CPU time consuming.

fill_mesh_holes_and_boundary algorithm doesn't yet prevent from creating self intersecting faces, neither it ensures mesh curvature continuity. For these reasons it is mostly efficent on flat holes for the moment.

clone_solve_nmnfld_vertices may create flat triangle(s). I still have to figure out why and how to avoid it. However it is still possible to remove them a posteriori with the function remove_flat_triangles.

Curvature computation algorithm is a homemade temporary version. It is mostly efficient on regular meshes (where all faces have more or less the same size, and all the vertices have the same valence).

%% MISC INFORMATION

Most of the time, I did my best to make function names are pretty explicit in english.
By default, vertex and face normals are normalized at the same time they are computed.
Basic 3D mathematical computation algorithm (like point_to_plane_distance) are also independently available with their documentations in my file exchange contributions.
Since I am not native english speaker, please forgive my langage approximations.
I especially thank William V, Binbin Qi, for what they taught me.

### Cite As

Nicolas Douillet (2020). Mesh processing toolbox (https://github.com/NicolasDouillet/mesh_processing_toolbox/releases/tag/v1.2), GitHub. Retrieved .

Lao Schin

Pretty clean work.

Nicolas Douillet

[Description too short to fit, here below is the following]

Matlab users, your advices and tips to improve and speed up my algorithms are welcome !

I you can’t see the mesh while plotting it, try ‘shading flat’ (it may be shadowed by its numerous dark edges).

Difference between find_triangles_from_vertex_list and find_triangle_sets_from_vertex_list functions is that in the first case all triangle indices are put together in a matrix container, whereas in the second case they are sorted by vertex in a cell array.
Difference between show functions and select functions is that the last ones return the selected object as an output (whereas show functions return nothing).

Gargoyle meshed models are provided courtesy of VCG-ISTI by the AIM@SHAPE-VISIONAIR Shape Repository.
Armadillo is a simplified version of the one you can find on Stanford 3D scanning repository : https://graphics.stanford.edu/data/3Dscanrep/

Matlab release version used for development and tests : R2019b.

Last update : june 2020, wednesday the 17th.

##### MATLAB Release Compatibility
Created with R2019b
Compatible with any release
##### Platform Compatibility
Windows macOS Linux